He snatched $4,000 in cash and ran, but did not get far.
The 56-year-old man had barely run 30m before he ran out of breath and was pinned down by security.
Chinese daily Lianhe Wanbao reported that the incident happened on Tuesday at around 3.20pm.
The man snatched the money from a customer in front of a remittance service counter on the second storey of People's Park Complex.
The security guard, who gave his name as Mr Jason, said: "I thought the two men knew each other and were just playing, but then I heard shouting and saw the man run down the stairs.
"It was then I knew something was wrong and I gave chase."
Mr Jason did not have to chase the man very far.
Passers-by said the man had run out of breath and starting panting heavily by the time he got out of the complex.
Mr Jason jumped on him, pinning him to the ground.
"After he was pinned down, he kept reaching for his back pocket, like he was looking for something," said Mr Jason, who confiscated a 10cm-long knife from the man's pocket.
"I guess he was trying to get the knife and escape."
Two other security guards helped Mr Jason as they waited for the police to arrive. The police said they received a call at 3.22pm.
A police spokesman said: "A 56-year-old man was arrested for suspicion of theft. Police investigations are ongoing."
Mr Jason returned the money to the owner.
He said: "It's my job. My other colleagues would have done the same."
This article was first published on Jan 29, 2015. Get The New Paper for more stories.